Application of coverings to wires applicable to the insulation of electric conductors and to other purposes



Nov. 13, 1934. NlSBETT I 1,980,694 A APPLICATION OF COVERINGS TO WIRES APPLICABLE TO THE INSULATION 0F ELECTRIC CONDUCTORS AND TO OTHER PURPOSES Filed July 16, 1952 4 Sheets$heet 1 Fig. 1

ATTORNEY Nov. 13, 1934.

APPLICATION OF COVEHI G. H. NISBETT NGS T0 WIRES'APPLICA 0F ELECTRIC CONDUCTORS AND TO OTHER PURPO Filed July 16,

1,980,694 BLE TO THE INSULATION SES 19:2 4 Sheets-Sheet v 2 Fig. 3.

Fig. 5,

G. H. NISBETT Nov. 13, 1934. 1,980,694

APPLICATION OF covsnmes TO wmzs APPLICABLE TO THE msumvrrou OF ELECTRIC CONDUCTQRS AND 1'0 OTHER FUR Filed July 16, 1932 4 Sheets-Sheet 3 I? ii 4 INVENTOR ATTORNEYS 1934- G. H. NlSBETT 1,980,694 v APPLICATION OF COVERINGS.TO wmss APPLVIGABLE To THE INSULATION OF ELECTRIC CONDUCTORS AND TO OTHER PURPOSES T Filed July 16, 1932 4 Sheets-Sheet 4 l/YVENTOR ,414.1 5y

ATTORNEY:

Patented Nov. 13, 1934 UNITED STATES'PATENT OFFICE APPLICATION OF COVERINGS To WIRES AP- Q PLICABLE To THE INSULATION F ELEC- TRIO CONDUCTORS AND TO OTHER PUR- l POSES George Hinde Nisbett, Lancashire, England, as-

signcr to British Insulated Cables Limited, Lancashire, England, a British company 9 Claims.

This invention relates to the application of a covering of paper to wires and in particular, but not exclusively, to the insulating of electric conductors. The invention comprises the form of the covering and the method of and apparatus for applying this covering. The member to which the covering is applied may be a single wire or a group of wires, either stranded or bunched together. The wire or group of wires may be of circular or other section and may be bare or may have already received a suitable insulating or protective covering prior to the application of the paper. For convenience the member to which the covering is applied will be hereinafter referred to by the general term wire.

The method of covering which the invention provides is particularly advantageous when used on small sizes of wires, but the invention is not limited to such cases. 0 The object of the invention is to provide wires with a covering of paper by a method which permits of the rapid production of large quantities of covered wire in a single machine and also provides a covering which effectively encloses the wire and does not contain or need not contain any material in addition to the paper. No adhesive or binder is necessary.

t is to be understood that the term paper used herein is to be applied in a broad sense. It indicates a comparatively thin sheet material formed of fibres felted together. A large proportion of the fibres will be of vegetable origin, but the paper may contain mixtures of animal fibres or of mineral fibres (for instance, of asbestos).

It is also to be understood that the term sheet used in connection with paper may include two or more superposed layers which may or may not be of the same nature. I

The covering for a wire provided in accordance with the present invention consists of a paper tube formed of a single strip bent round the wire or of two strips each bent to form a part, usually half, of the tube, the tube being completed by one seam or by two seams running longitudinally produced by the combined action of moisture and heavy pressure.

The making of the seam proceeds in the same manner whether a single strip or two strips of paper are used in the production of the tubular covering for a wire. The method employing two strips is the more generally applicable for reasons which will be made apparent from the following description. It will, therefore, be described first and reference will be made subsequently to the modification necessary where each tube is formed from a single strip.

The method'employing two strips of paper may be carried into effect with a single wire or with a number of wires lying side by side. The latter arrangement is generally adopted and the possibility, which it gives, of covering simultaneously a large number of wires constitutes one of the most important advantages of the invention. p In this method the single wire or a number of wires side by side are fed with two sheets of moistened paper, in the form of strips of appropriate width, one lying above and the other below the Wires, between a pair of grooved rolls. Each of the grooves is of semi-circular or of other suitable form and each groove in one roll registers with a corresponding groove in the other and together they enclose a space which will contain a wire and the surrounding paper. The grooves are spaced apart laterally at appropriate distances along the surface of each roll. As the two sheets of paper with the Wires between them approach the rolls, there are continuous strips of paper ofuniform' thickness above and below a number of equally. spaced wires. The portions of the surface ofeach roll which stand between adjacent grooves are held close to the same portions of "the surface of the other roll and as the sheets of paper pass be tween these portions, they are strongly compressed. By the combined action of the water in the paper and the heavy pressure exerted by the rolls on the paper, a seam is formed between the two sheets at each side of each groove. 7

An important function of the moisture in this method of making the seams appears to be the loosening of the interlocking of the fibres in the. sheets so that the fibres in the paper sheets, at the edge of each groove, can be forced by the pressure exerted on them by the rolls to move into new positions. There is a certain minimum limit to the water content to be given to the paper in order that it may be effective for they purpose indicated. This limit can be readily ascertained by trial. Since however there does not appear to a practical maximum limit to the 100 quantity of water carried by the paper, as far as the elfectiveness in the present method is concerned, it is generally only necessary to ensure that an ample quantity of water is carried by the paper. The excess is squeezed out in passing 105 through the rolls. I

There is also a lower limit to the degree of pressure exerted by the rolls in order to make an effective seam. This limit can readily be ascertained by trial, for instance, by adjusting pressure screws on the bearings of one of the rolls gradually until an effective seam is produced. It will then be found that the thickness of the paper in the parts which lie outside the grooves has been greatly reduced; This-reduction can, in fact, often be carried to the point at which there is not sufficient of the fibres remaining between adjacent covered wires as they leave the rolls to maintain continuity across the composite strip of wires and paper. In general however it is preferable to make the seam by using a lower pressure which leaves a thin but definite web of paper between adjacent wires. One of the advantages of this is that it ensures the strip travelling forward as a whole. In the thin webs remaining between the wires, 'it is generally impossible to detect the existence of two layers of paper. The two sheets of paper have here been joined together. This joining extends into the grooves, and, at least in part, causes the production of the seams. From an examination of the product itappears clear that the action is not that of simple compression. The reduction in the thickness of the webs located between the wires in the strip is not completely accounted for by compression. There is also evidence of lateral displacement of some of the material of the paper sheets from the web into the grooves. During this displacement it is probable that re-arrangement of the fibres of the two sheets takes place and this is probably accompanied by some interengagement of the fibres of one sheet with those of the other. In some cases also it appears that those parts of the two sheets which have moved laterally into the grooves have been rolled or folded up together. All of these effects can contribute to the production of the seam. Perhaps also there may be a physical or chemical change in the condition of the fibres brought about by the combination of high local pressure and moisture.

For instance there may be a local gelatinization of the surfaces of the fibres or existing gelatinization may be made more effective in producing adhesion under the intimate contact. brought about by the exertion of heavypressure on the fibres when in contact with water. Whatever may be the cause or group of causes resulting in the formation of the scam, the prime requirement is the combination .of moisture and heavy pressure exerted in the manner indicated. -By this means an effective seam is produced without the necessity for employing anythingof the kind usually known as an adhesive. This is an important advantage and has a notable value in connection with certain insulated wires, particu,

larly the conductors for telephone and other communication cables, where any such foreign substance introduced into the covering of the wire can have an eilect on the electrical properties of the cable.

It will be seen, from the preceding description,

that the product coming from the grooved rollsis a strip of paper in which are embedded a ;number of parallel wires so that each .Wire is stage. Accordingly the strip leaving the grooved These webs rolls is passed through a drying arrangement and is subsequently carried .to the separating device. By this means each wire fed into the machine is delivered finally with a covering in the form of a paper tube made from a strip or from two'strips of paper which have been seamed longitudinally by the combined action of the moisture carried by the paper and the heavy pressure exerted on it.

The paper tube may form a closely fitting covering on the wire and may be a plain tube or may be provided with external longitudinally extending ribs. Alternatively the tube may form an oversize or loose covering, that is a covering of greater internal circumference than the external circumference of the wire which it encloses, so that there is free space between the surfaces of the wire and the paper at one or more places in the final product. The diiierences between these several types of covering are dependent upon the form and dimensions of the grooves in the rolls in relation to the shape and dimensions of the wire.

In providing wire with a ribbed covering an appropriately shaped recess (or recesses) is pro vided in the surfaces of the groove (or grooves). The number of recesses is obviously dependent upon the number of ribs to be provided. The recesses may be so placed as to form a single rib or a pair of ribs at the places where the two sheets of paper meet and are formed into a seam. This is done by providing, in addition to the parts of the rolls which give the high compression, ad-

jacent recessed parts which directly adjoin the grooves and leave a sufiicient space between them for the formation of ribs of the desired width. This will in general involve an increase in the distance between the grooves in the rolls so as to provide space for the high compression region and one or more ribs.

Where more than two ribs are required they may be provided by making recesses of the appropriate depth and width in the surfaces of the grooves in the rolls. Four ribs can be provided by forming two ribs at the junctionbetween the two sheets, as previously indicated, and two more ribs, each produced bymeans of a recess in the bottom of each of the main grooves in the roll.

In order to provide for the production of these ribs it may be necessary to use paper of greater thickness than would otherwise sufiice for the obtaining of the desired radial thickness of covering on the wire.

Wire with a ribbed covering is particular1ysuit-- able for use in telephone cables where the ribs serve for spacing apart the individual wires. A ribbed covering of this kind may also be employed for the purpose of providing means of id'entifica tion' of different conductors in acable, the distinction being made, for instance, by varying the number of ribs. or by providing some wires with ribs and others without.

In producing an oversize covering each pair of grooves is made of such dimensions that it encloses a space of greater size than is necessary to accommodate a wire and two thicknesses of paper. This is preferably done by making one or both of the grooves deeper than the radius of the wire plus the thicknessof the paper. Some excess in the width of the grooves is also advantageous or permissible. Hence for round wire we may make each groove of semi-circular form with a radius somewhat greater than the radius of the wire plus the thickness of the paper.

It appears that the loose covering is formed-in the following manner. When a wire and the two enclosing layers of moistenedpaper are passed between the rolls with grooves of this kind, the parts of the paper projecting laterally from the grooves are forced to move inward by the pressure exerted on them and the efiect of this is to fill up the space between the wire and the adjacent edges of the grooves on each side of the wire with a compressed body of interengaging fibres from the two layers. This filling up of the space between the wire and the surfaces of the grooves only proceeds to a short distance on each side of the meeting surface of the paper layers so that the rest of the paper stands clear of the wire by a short distance. The result of this action is the production of a wire enclosed in a tube which is slightly oversize. This form of covering is particularly advantageous for wires which are to be used in the manufacture of telephone cables.

In order to provide a smooth surface on the outside of the paper it may be desirable in some cases to give the paper a treatment after separation from the strip in which, by a rotary stroking action, any fibres projecting at the seam or seams be removed or caused to lie on the surface of the covering of the wire. This may be done by applying to each wire, a rotary rubber which preferably travels at a comparatively high speed relative to the surface of the paper.

In the form of the method in which a single strip of paper is used the general method of applying the paper to the wires is modified in the following Way. This modification is more particulariy suitable for dealing with comparatively large wires. The single sheet of paper is fed to the grooved rolls in such a way that it is folded round one wire or two adjacent wires so as to form a tube having a single seam for each wire. In the case of a single wire the paper would be folded completely round it and the two edges brought together so as to be compressed between the edges at one side of the groove. In the case of a single sheet applied to two wires the paper would be folded over from the two sides round the two wires so that the two edge portions would come to lie between the circumferential walls which separate the two grooves of each roll. In order to ensure the making of continuous seams, it will be advisable to make these circumferential walls wider,

T in this case, than in cases where two sheets are used. One or both of the walls may be provided with a central recess, running round its periphery into which surplus material from the compressed parts of the paper can pass.

The invention will be further described by the aid of the accompanying diagrammatic drawings. In these Figure 1 indicates the general arrangement of a machine for covering a number of wires simultaneously in accordance with the invention. Figures 2, 3 and 4 show details of the pressure rolls. Figure 5 is a plan view indicating the manner in which the strip of covering wires is divided up and Figures 6 and 7 show details of the pressure rolls for use in cases where ribbed coverings are to be applied to wires. Figure 8 indicates the modification which would be introduced into Figure 1 for the case where two wires are being covered by means of a single strip of paper. Figure 9 illustrates an arrangement for treating a covered wire for the purpose of removing projecting fibres at the seams.

In Figure l the wire travels from left to right. It is drawn off the supply reels 1 over the guide rolls 2 and 3 and between the pressure rolls 4. At these rolls it meets the two strips of paper 5 coming from the rolls of paper 6. This paper is thoroughly moistened with water before it reaches the rolls 4.. This can be done by a moistening device placed between the rolls of paper 6 and the pressure rolls 4, but this is not done in the case illustrated. The rolls of paper 6 have been thoroughly moistened previously to being placed on the machine. It is found that rolls of paper treated in this way can be kept in a closed container for a considerable length of time without losing moisture to a sufficient extent to become unsuitable for use. The lower pressure roll 4 is positively driven and imparts movement to the upper roll 4.- by friction. The pressure between the rolls is adjusted by means of the screws '7 acting on the bearings of the upper roll 4. I

The product of these pressure rolls 4 is a strip 8 composed of -wires covered with paper and connected by thin webs. The strip passes round the cylinder 9 to the roll 10 and from there it passes into the drying chamber 11 which is in the form of a long horizontal tube with a narrow opening at each end,'one of them being shown at 12, and having guide rollers 13 on which the strip 8 rests as it passes through the chamber. Hot gas enters the drying chamber by the duct 14 and leaves by the duct 15 carrying with it the moisture given oil by the strip 8 in drying. When the dry strip leaves the right handend of the chamber 11 it passes round a cylinder 16 and is then carried back to a number of rollers 17 on which it is divided up into its component wires which are led oii to the reels 18.

The cylinders 9 and 16 are driven from an external source of power not shown and carry forward the strip 8. Each of the reels 18 is also driven. In this case it is preferable to apply the drive to each reel through, a separate friction clutch which will permit slipping to take place.

It is emphasized that the drawings are entirely diagrammatic and that many ordinary mechanical features, which are required to make a complete machine, are omitted with the object of avoiding the obscuring of features of the invention. As already indicated the drives for rotating those shafts'to which power is'directly applied are not shown. These shafts have however been indicated by applying X as a marking on the end of the shaft in Figure 1. Similarly the mechanism by which the-guide forks 19 are reciprocated is not indicated. This is mechanism of a well known kind.

Also for the sake of clearness only siX wires have been shown as being dealt with in the machine. Usually a much larger number will be covered simultaneously in one strip. For instance, the number may be sixty when dealing with small wires.

Figure 4 is intended to indicate the relative proportions of the grooves 22 of the pressure rolls t and the spaces between these grooves. The drawings are made on an enlarged scale for the case where wires 23 of about 20 mils. (.50 mm.) diameter are being covered with paper 7 mils. (.175 mm.) thick. For the case of a closely fitting covering the grooves are made of dimensions which permit them to enclose the wire with a surrounding space equal to the thickness of the paper sheet to be applied. In this case the diameter of the circle formed by the two registering grooves would be approximately 34 mils. (.85-mm.). If it is desired to obtain an oversize covering the same grooves would be used for the same thickness of paper sheet with wire of a smaller diameter. For instance, wire of 15 mils. (.375 mm.) diameter. This is indicated by the circle in broken lines. This figure also indicates the proportional distance by which the grooves are spaced apart on the rolls. No space is shown. between the portions of the surfaces of the pressure rolls which stand between adjaoent grooves since no such space can be directly observed. It is probable that the separation which is necessary for the passage of the thin Web is produced by local deformation of the rolls.

' In Figures 2 and 3 complete departure is made from the proportionality indicated in Figure 4. This departure is made with the object of showing features clearly. These figuresl show the guide plate 21, the position of which is also indicated in Figure 1. The object of this plate is to keep the wires in their correct relative positions and in line with the grooves as they appreach the pressure rolls 4. The holes are of such dimensions that they provide comfortable clearance for the smooth running of the wires through'them.

In Figures 6 and 7 are shown the form and relative proportions of the wires and grooves in two pairs of pressure rolls arranged for the production of coverings having ribs. In the case of Figure 6 there are two ribs to each wire. In the case of Figure 7 four ribs are indicated. Two ribs in each-case are produced by the formation of recesses 24 adjoining the grooves 22 and extending laterally from them along the surfaces of therolls. This involves an increase of the distance between the centres of the grooves 22 as compared with the case such as shown in Figure 4.

The additional ribs provided for in Figure 7 are produced by means of the additional recesses 25 in the bottom of each of the main grooves 22 in the rolls. It is found that the recesses 25' should be materially deeper than the ribs which are to be produced in them. The paper is forced into these grooves approximately to the 'extent indicated by the hatched part.

In'general it is found that the webs connecting thev several wires in the strip can readily be severed by a tearing action. The manner in which this is carried out is indicated in Figure 1 and in Figure 5. As the dry strip 8 passes over the first of the rollers 17, the two outermost wires of the strip are drawn downward round the roller and pass through appropriate guide forks 19 (carried by reciprocating bars 26) on to the appropriate reels 18. At the next roller 17 the two outermost wires now remaining in the strip are separated and this process is continued until completed. In the case of the example illustrated where there are six wires, it is of course only necessary to employ three rollers 17. i In general, as previously indicated, the number of wires and the corresponding number of rollers will be materially greater than these.

In arranging the rollers 17 in relation to their reels 18, it is important to ensure that the wires in thecourse of being severed from the strip are pulled'firmly down against the surface of the roller 17. This result is attained by disposing each beyond the point at which they lie vertically under the axis of the roller 17. It will be seen from Figure 5 that the arrangement indicated complies with this requirement with an 1 appreciable margin. Under these conditions the detachment of each wire from the'strip takes place on the surface of the roller and therefore the .pull of separation does not disturb the path of the strip 8. Satisfactory separation by tearing will then take place.

Where it is important to have a very smooth finish on the surface of the covered wire, arrangements such as shown in Figure 9 may be employed for the purpose of removing any fibres which may project at the seam. This treatment is most conveniently given to each wire separately after it has been coiled up on the reels 18 and removed from the main machine. Each wire is then run through one or more devices of the kind shown in Figure 9. In that figure the covered wire 30 passes from left to right between a pair of bufiing rolls 31 which are rotated rapidly by their spindles 32 so as to exert a wiping or stroking action on the surfaces of the covering of the wire. Each roll consists of a number of discs of cloth which are sufficiently flexible to permit the passage of the covered wire 30. During this passage any projecting fibres are removed. In the drawings such fibres are indicated diagrammatically at 33 on the left part of the wire 30. It is to be understood that for the sake of clearness the covered wire is shown in this figure. on an enlarged scale.

When the variety of the method of covering in which a single strip of paper is wrapped round two wires is to be employed, the construction of the left hand end of the machine shown in Figure 1 will be modified in the manner indicated in Figure 8. The two wires 34 are drawn from reels (not shown) at the left hand side of the figure and enter a folding guide funnel 35 together with a strip of paper coming from the paper roll 36. In this funnel the strip of paper, which lies beneath the wires, is folded over at each side so as to enclose the two wires and overlap at the middle parts. This is done while the paper is dry. The wires with the paper wrapping then pass through a bath of water 37 in which they are guided by a roller 38. After thorough moistening of the paper in this bath, the strip consisting of the two Wires and the paper wrapping passes to a pair of pressure rolls 39 which are similar in. their action to the rolls 4. of Figure 1. From this point the strip passes round suitable guides such as drum 9 and roller 10 of Figure 1. In this case there is only one seam formed in the covering of each wire. This is produced in the space betweenthe two wires by the action of the rollers 39 on the overlapping parts of the strip of moistened paper.

In connection with this variety of the method of covering it is to be noted that thetwo wires 34 are fed into the folding device 35 lying close together and the paper is folded round them While they are so placed. Between this point and the engagement of the lower pressure roll 39 the wiresare gradually spread apart to a sumcient extent to suit the spacing of the grooves. This has the effect of drawing the paper tightly against the outer sides of the wires so that there is no slack paper at those places which might be engaged by the rolls at the outer edges of the two grooves. This procedure necessitates a comparatively longpath between the bath 3'7 and paper coverings of different wires.

the lower roll 39 and it also requires that the wrapped wires should encounter this roll 39 at wires take up their positions in the grooves be-' fore they reach the place at which the compression of the paper is to be effected.

The method of covering provides for the application of coverings of a considerable range of thickness. The application may be effected in a single treatment or by repeated treatment. In the latter case the wires after passing through the machine and receiving one covering may be passed through again to receive another covering superposed on the first and this process is repeated the required number of times. Alternatively a number of pairs of pressure rolls may be arranged to apply successive coverings to a set of wires without subjecting each covering to drying before the next is applied. In this case the covering is built up in layers of wet paper to form a strip which is then dried.

It will also be seen that this method of coveringprovides facilities for giving distinctive characteristics to the appearance of diiferent insulated wires such as are required, for instance, for the identification of the different conductors of a multicore cable. Distinction can be obtained by the use of different colours for the A wire may be covered with paper of the same colour on the top and bottom sides or sheets of different coloured paper may be employed for application simultaneously to the two sides of a group of wires so that each wire is covered on one side with one colour and on the other side with another colour. Alternatively, different colours may be used in different superposed layers. Instead of, or in addition to colours, marking on the paper 'can be employed as a distinctive characteristic.

This marking may be applied to the paper before it comes to the wire, or may be made on the surface of the finished insulation.

It will be understood that the detailed de- 'scription given in conjunction with the drawings only sets out one example or type of the apparatus for carrying out the invention. It may be modified to a considerable extent within the scope of the invention. While round wires have been indicated in the drawings dealt with by means of semi-circular grooves, it is to be understood that there is no limitation of themethod to this form of wire. For instance, square wire may be dealt with by the use of rectangular grooves. It will be understood that the invention is not limited to any particular form of drying arrangement. Many suitable alternative forms of such arrangements are well known. An entirely difierent method of removing the water may be employed where it is desired to impregnate the paper with some other liquid. In this an impregnating material is used of a boiling point materially higher than that of the moisture to be removed, and the strip is drawn through a bath of this impregnating material, which is kept at a temperature above the boiling point, of water. By this means the moisture is driven off and escapes as vapour from the surface of the bath and at the same time the paper is impregnated.

Although separation by tearing has been indicated as an effective method of breaking up the strip into its component wires after drying, it will be understood that other methods may be employed. Where the covering is of thicker material or .for 'other'reasons it is ,found desirable-to leave a thicker web between wires in the strip than in the case dealt with in the example, it may be advantageous to employ cutting. rolls or. knives for severing the webs.

What I claim as my invention and desire to secure by Letters Patent is l. A method of covering wire with paper in which the wire andthe moistened paper above and'below it are fed between two rolls, the wire and paper passing through the spa'ceformed by registering grooves in said rolls with a portionv of both the upper and the lower paper extending laterally from this space on at least one side .of the grooves, the paper being joined by causing adherence between the upper and lower parts by the combined action of the water in the paper and of the heavy pressure exerted by the rolls.

2. A method of covering wire with paper in which the wire and the moistened paper above and below it are fed between two rolls, the wire and paper passing through the space formed by registering grooves in said rolls: with a portion of both the upper and the lower paper extending laterally from this space on at least one side of the grooves, and in which a seam is formed between the up-perand lower parts of the paper within the said space by forcing a substantial proportion of the material in the laterally extending portions of the paper to move laterally into the grooves so that the moistened parts interengage there under the influence of the pressure upon the rolls.

3. A method of covering wire in which a sheet of moistened paper is bent round a wire and the wire and the moistened paper surrounding it are fed between two rolls, the wire and paper passing through the space formed by registering grooves in the said rolls with the edge portions of the sheet of paper extending laterally from this space on one side thereof, the paper being seamed at this side by the combined action of the water in the paper and the heavy pressur exerted by the rolls.

4. A method of covering wire in which the 'wire isplaced between two sheets of moistened paper and the wire and paper are fed between rolls into the space formed by registering grooves in the said rolls with both sheets of paper extending laterally from this space on both sides of the grooves, the said sheets being joined together at both sides of the grooves by causing adherence between them by the combined action of the water in the paper and the heavy pressure exerted by the rolls.

5. A method of covering simultaneously a number of wires in which the wires are placed side by side between two sheets of moistened paper and the wires and sheets are passed through a pair of pressure rolls, the wires passing in the spaces formed by registering grooves in the said rolls, and the paper sheets, in the parts lying between the side grooves, being strongly compressed and the material of these parts,being mainly forced into the grooves so as to leave only thin webs, after which the strip, containing the covered wires connected by these thin webs, is dried and the individual wires are subsequently separated by severing the webs.

6. A method of covering wire in which the wire with moistened paper above and below it is passed between rolls in the space formed by registering grooves in the said rolls and in which at least one longitudinal ribis formed on the surface of the paper covering by the forcing of the paper into an appropriately shaped recess in theroll surface enclosing said space.

7. A method of covering wire with paper in which the wire and the moistened paperabove and below it are fed between two rolls, the wire and paper passing through the space formed by registering grooves in said-rolls with a portion of both the upper and the lower paper extending laterally from this space on at least one side of the grooves, and in which a longitudinal rib embodying auseam is formed on the surface of the covering by forcing a substantial portion of the-material in the laterally extending portions ofthe paper to move laterally under the pressure exerted by the rolls into shallow recesses in adjoining the'grooves in the faces of the rolls.

8. A method of providing a. wire with an oversize or loose covering of paper in which the wire and the moistened paperabove and below it are fedgbetween two rolls, the wire and paper passing through the space formed by registering grooves in said rolls with a portion .of both the upper and the lower paper extending laterally "f from this space on at least one side of the grooves,

this space being greater than is required,

in order to accommodate the wire and the covering of paper, and in which a seam is formed between the upper and lower parts of the paper within the said space by forcing a substantial proportion of the material in thelaterally extending portions of the paper to move laterally into the grooves so that the moistened parts interengage there under the influence of the pressure upon the rolls and thereby only partially fill up the surplus space within the grooves. I

9. In a machine for covering simultaneously a number of wires with paper by passing the wires,

with moistened paper above and below them, be- I tween a pair of grooved rolls and drying the composite strip which issues/from the rolls; an arrangement for separating the wire from the strip, comprising a curved guide surface, means for leading the strip in contact with said surface and means for diverting a wire from said strip over said curved surface so that separation between the strip and the wire takes place on said 

